fix: incorrect accessor reference in OIDCService

During development a property named `success` was inverted to a property
named `failed` which resulted in an incorrect accessor reference with a
referring piece of code that wasn't updated. This is type error.

src/backend/src/services/auth/OIDCService.js

@@ -234,7 +234,7 @@ export class OIDCService extends BaseService {
             assume_email_ownership: true,
         });
         const { user_id } = outcome.infoObject;
-        if ( outcome.success ) {
+        if ( outcome.succeeded ) {
             await this.linkProviderToUser(user_id, providerId, claims.sub, null);
         }
         return outcome;

src/backend/src/util/outcomeutil.js

@@ -7,6 +7,9 @@ export class OutcomeObject {
     fields = {};
     ended = false;
     infoObject;
+    get succeeded () {
+        return this.ended && !this.failed;
+    }
     constructor (infoObject) {
         this.failed = true;
         this.userMessageFields = {};